"We didn't take your fingerprints to convict you." Liu Pancheng patiently explained the last bit of temperament, "On the contrary, this is done to protect you, to exclude your fingerprints from a pile of fingerprints, then the remaining ones are the fingerprints of criminals." If you don't let us take your fingerprints, how can we distinguish your fingerprints from those of the bad guys? ”

"That's right!" Aunt Tian said with relief, "Then you remember to collect Aunt Wu's fingerprints too!" She also came in and out through this door. You must not mix her fingerprints with the fingerprints of the bad guys! ”

"Who is Aunt Wu?" Liu Pancheng looked at Aunt Tian suspiciously.

"She is the aunt we hired to cook lunch and dinner for the staff on duty." Deputy Director Qu added on the side.

"Where's she?"

"She hasn't come yet, she doesn't usually come to work until half past ten."

"What about off-duty hours? What time does she get off work? Liu Pancheng asked.

"It's usually around six o'clock, and she goes home after cooking dinner for the staff on duty."

"In other words, she was the last one to leave."

"So to speak."

"The back door of the police station was locked after she left?"

"Not really." Deputy Director Qu further explained, "The back door of the police station is usually locked before 10 o'clock that night, that is, before going to bed. ”

Liu Pancheng propped his elbows, stroked his chin, and fell into thought again.

"Leader, can I go?" Aunt Tian saw that Liu Pancheng stopped talking, so she couldn't wait to ask out loud.

When Liu Pancheng heard this, he didn't say anything, just waved at her and motioned to Deputy Director Qu to take her out to collect fingerprints.

"Team Liu." Wang Kui didn't know when he had returned to the conference room on the second floor, "There is indeed a police 64-style pistol missing in the gun magazine, and the recipient registered in the receipt book is Liu Suo." ”

Liu Panchang breathed a sigh of relief, both with the emotion in his words and the worry that the situation would deteriorate further.

"There are ......," Wang Kui continued with a dark face, "just now the comrades of the Criminal Division Institute extracted two footprints of the same size as those in the dormitory at the entrance of the back door of the police station. Our previous analysis is likely to be accurate, and the killer did enter the police station through the back door. Moreover, judging from the current situation, there is only one murderer. I have already asked the comrades of the Criminal Division to go to other office areas to investigate again, and if there is no further discovery, there is a good chance that this murderer is coming at Liu. Perhaps, Liu specially chose to invite the murderer to the police station to meet him when he was on duty. It seems that we need to start with the interpersonal aspect of Liu. ”

"What about the locks?" Liu Pancheng frowned.

"Intact." Wang Kui replied in a deep voice, "The comrades from the Criminal Department have already taken the fingerprints on it. But ......"

"It's not easy to extract, is it?" Liu Pancheng guessed.

"Yes." Wang Kui nodded and said, "There are really a lot of people coming in and out of the back door, and the fingerprints on the door are disorganized, and it is difficult to extract any complete and effective fingerprints." Wang Kui paused and added, "Even if these fingerprints can be separated one by one, there are thirty or forty people entering and exiting through this back door every day, and everyone collects fingerprints once, and it will take a lot of time to compare them one by one." For a while, I'm afraid it will be difficult to get a breakthrough from fingerprints. ”

"Do people here go to and from work through the back door?" Liu Pancheng continued to pursue unmoved.

"Most people!" Wang Kui didn't dare to say anything, "According to what I learned about it just now, the general reaction of the people in the institute is that Liu's police appearance and discipline are still relatively strict. He once made it clear that no personnel wearing uniforms were allowed to enter or leave through the main entrance, for fear of being seen by the common people and causing some unnecessary public opinion. ”

"Wang Kui, I've been thinking since just now, could this be an acquaintance?" Liu Pancheng put his face to Wang Kui's ear and whispered, "You also saw just now, Liu's bedroom is very neat, which is completely different from the situation presented at ordinary crime scenes. We've seen a lot of crime scenes, and how many of them are upstairs? I felt that the murderer was not panicked at all when committing the crime, he seemed very calm, and there was a feeling of calm and leisurely. ”

Wang Kui nodded and agreed: "The murderer's modus operandi is extremely sophisticated and ruthless, and the murder weapon is very sharp. This person is either a repeat offender or a person with extremely strong psychological qualities. But I really can't think of it, how could Liu Suo know such a person? How can you form a grudge against such a person? ”

"Could it be that ......" Wang Kui's eyes suddenly widened in surprise, and he opened his mouth and gasped twice, "Is it the person who was dealt with by Liu before, and came to take revenge after being released from prison?" Immediately, he shook his head and denied, "No, no, that footprint...... But that footprint was clearly related to the gang of criminals who robbed the cash truck...... Could it be that the robbery of the cash truck is also ......"

Liu Pancheng waved his hand, interrupting Wang Kui's unruly speculation like a wild horse, and said, "Footprints can be forged. ”

"Fake footprints? How do you think that? Wang Kui asked puzzledly, "Divert your gaze?" Blaming others? Interfering with the case? Wang Kui was puzzled, and then said with a smile, "Team Liu, you are more unreliable than me when you think about it!" We haven't found that Pan Wang yet, and we don't know if he really has big feet. Even if there were, we don't have direct evidence that he was involved in the cash truck robbery. What's the use of the murderer making a big footprint and linking it to the cash truck robbery? Is it because Liu is a case handler who is investigating this case? Also, if the murderer wants to forge footprints, he must not know in advance that we are checking the big footprints! The clues of our investigation are all confidential, how can outsiders ......" Wang Kui's series of nagging came to an abrupt end, and he suddenly glared at Liu Pancheng, "So what do you mean by acquaintances...... The neat killing methods and tough psychological quality are indeed something that only professionally trained people can do. Immediately, Wang Kui suddenly seemed to think of something, and said without words, "Team Liu, what do you think of the modus operandi of the cash truck robbery?" Is it very similar to the murder of Liu this time? Sophisticated, ruthless, and clean. The three victims all had only one fatal wound to their heads, which shows that the murderer was steady and ruthless. Moreover, apart from the debris left by the vehicle impact, there were no other footprints or fingerprints at the scene to solve the case. The main thing is that there was also no physical contact between the three victims and the murderer, let alone fighting. Isn't the two cases similar? ”

Liu Pancheng nodded in agreement: "This is also what I can't figure out." ”

"Hypothetical, I mean hypothetical......" Wang Kui glanced at Liu Pancheng, carefully considered the wording, and said slowly, "Our blind analysis is valid, the murderer of Liu Suo is the robber who robbed the cash car, then his purpose in killing Liu Suo is likely to be the key clues that Liu Suo has that we don't know." So how did he know that Liu had the key clues? Wang Kui said as if asking himself, "Combined with our analysis of the scene of the murder of Liu, it can be seen that the murderer and Liu should have known each other, and the methods displayed by the murderer when committing the crime show that he is a professionally trained person, and this person may be our internal comrade." By the way, Team Liu, didn't you always suspect that there were bank insiders involved in the cash truck robbery? Could it be that it's not the bankers, but ours? If someone uses this as a monitoring point, it would be easy to find out the pattern of cash trucks, and it would be very effective to avoid people's eyes and arouse suspicion. Perhaps, Liu Suo recognized the murderer of the secret accomplice. ”